It is a well-known fact that manufacturing plants designed for a particular type of vehicle only achieve their full potential, when a new model is introduced, after a certain start-up phase and, when a model change is imminent, operate at less than full capacity. Such operation of a manufacturing plant is not economical. Therefore there are considerations as to how the economy of the manufacturing plant can be improved in the startup phase and final phase of a vehicle model.
Furthermore it is only possible, to a quite limited extent, to run a manufacturing plant with different vehicle models or pre-fabricated part types (in the following abbreviated to “types”). In order to run a manufacturing plant at full capacity it would therefore also be desirable to use it to produce a mix of different types.
Processing a free mix of different pre-fabricated part types is possible to a limited extent with a known manufacturing plant (DE 298 13 669 U1). With this manufacturing plant the different pre-fabricated part types are supplied via pre-fabricated part feeders arranged separately next to each other or one above the other. By means of a multi-axial handling robot the prefabricated part types are transferred onto individual dollies, which can move to and fro transverse to the material flow direction, so that a dolly with one type of pre-fabricated part is located in each case at a workstation, while the other or others are in quiescent position. Each type of pre-fabricated part is held centrally in a lower tool on the dolly, which having an upper tool designed as gripper forms a clamping device. The gripper is detachably connected to a robot. The space requirement of such a manufacturing plant depends on the number of pre-fabricated part types to be processed. In addition a great amount of space is needed for the transverse movement of the dollies. For this reason the simultaneous mixed production of a plurality of pre-fabricated part types in such a manufacturing plant is possible with reasonable technical expenditure and floor space requirement.
In another known manufacturing plant for different prefabricated part types (DE 203 04 022 U1) processing stations, which in each case have several working locations for different pre-fabricated part types, are arranged along a transfer line. In order to be able to carry out work on the pre-fabricated parts at these various working locations, processing robots are displaceably arranged on axes of travel along the transfer line. Handling robots with which the prefabricated parts can be fed to and removed from the different working stations are also displaceably arranged on these axes of travel. With this manufacturing plant a great amount of floor space for the processing robots, arranged displaceably along the axis of travel, and working locations for the different pre-fabricated part types is needed. Although the majority of pre-fabricated part types can be processed through a correspondingly large number of workstations, the floor space needed for this is very great.